Copper electrodeposition in microelectronics

ABSTRACT

An electrolytic plating method and composition for electrolytically plating Cu onto a semiconductor integrated circuit substrate having submicron-sized interconnect features. The composition comprises a source of Cu ions and a suppressor compound comprising polyether groups. The method involves superfilling by rapid bottom-up deposition at a superfill speed by which Cu deposition in a vertical direction from the bottoms of the features to the top openings of the features is substantially greater than Cu deposition on the side walls.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/272,999, filed on Nov. 14, 2005, entitled COPPER ELECTRODEPOSITION INMICROELECTRONICS. U.S. patent application Ser. No. 11/272,999 claims thebenefit of U.S. Provisional Application No. 60/627,700, filed Nov. 12,2004, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to a method, compositions, and additives forelectrolytic Cu metallization in the field of microelectronicsmanufacture.

BACKGROUND OF THE INVENTION

Electrolytic Cu metallization is employed in the field ofmicroelectronics manufacture to provide electrical interconnection in awide variety of applications, such as, for example, in the manufactureof semiconductor integrated circuit (IC) devices. The demand formanufacturing semiconductor IC devices such as computer chips with highcircuit speed and high packing density requires the downward scaling offeature sizes in ultra-large-scale integration (ULSI) andvery-large-scale integration (VLSI) structures. The trend to smallerdevice sizes and increased circuit density requires decreasing thedimensions of interconnect features. An interconnect feature is afeature such as a via or trench formed in a dielectric substrate whichis then filled with metal to yield an electrically conductiveinterconnect. Further decreases in interconnect size present challengesin metal filling.

Copper has been introduced to replace aluminum to form the connectionlines and interconnects in semiconductor substrates. Copper has a lowerresistivity than aluminum and the thickness of a Cu line for the sameresistance can be thinner than that of an aluminum line.

The use of copper has introduced a number of requirements into the ICmanufacturing process. First, copper has a tendency to diffuse into thesemiconductor's junctions, thereby disturbing their electricalcharacteristics. To combat this occurrence, a barrier layer, such astitanium nitride, tantalum, tantalum nitride, or other layers as areknown in the art, is applied to the dielectric prior to the copperlayer's deposition. It is also necessary that the copper be deposited onthe barrier layer cost-effectively while ensuring the requisite coveragethickness for carrying signals between the IC's devices. As thearchitecture of ICs continues to shrink, this requirement proves to beincreasingly difficult to satisfy.

One conventional semiconductor manufacturing process is the copperdamascene system. Specifically, this system begins by etching thecircuit architecture into the substrate's dielectric material. Thearchitecture is comprised of a combination of the aforementionedtrenches and vias. Next, a barrier layer is laid over the dielectric toprevent diffusion of the subsequently applied copper layer into thesubstrate's junctions, followed by physical or chemical vapor depositionof a copper seed layer to provide electrical conductivity for asequential electrochemical process. Copper to fill into the vias andtrenches on substrates can be deposited by plating (such as electrolessand electrolytic), sputtering, plasma vapor deposition (PVD), andchemical vapor deposition (CVD). It is generally recognizedelectrochemical deposition is the best method to apply Cu since it ismore economical than other deposition methods and can flawlessly fillinto the interconnect features (often called “bottom up” growth). Afterthe copper layer has been deposited, excess copper is removed from thefacial plane of the dielectric by chemical mechanical polishing, leavingcopper in only the etched interconnect features of the dielectric.Subsequent layers are produced similarly before assembly into the finalsemiconductor package.

Copper plating methods must meet the stringent requirements of thesemiconductor industry. For example, Cu deposits must be uniform andcapable of flawlessly filling the small interconnect features of thedevice, for example, with openings of 100 nm or smaller.

Electrolytic Cu systems have been developed which rely on so-called“superfilling” or “bottom-up growth” to deposit Cu into high aspectratio features. Superfilling involves filling a feature from the bottomup, rather than at an equal rate on all its surfaces, to avoid seams andpinching off that can result in voiding. Systems consisting of asuppressor and an accelerator as additives have been developed forsuperfilling. As the result of momentum of bottom-up growth, the Cudeposit is thicker on the areas of interconnect features than on thefield area that does not have features. These overgrowth regions arecommonly called overplating, mounding, bumps, or humps. Smaller featuresgenerate higher overplating humps due to faster superfill speed. Theoverplating poses challenges for later chemical and mechanical polishingprocesses that planarize the Cu surface. A third organic additive calleda “leveler” is typically used to reduce the overgrowth.

As chip architecture gets smaller, with interconnects having openings onthe order of 100 nm and smaller through which Cu must grow to fill theinterconnects, there is a need for enhanced bottom-up speed. That is,the Cu must fill “faster” in the sense that the rate of growth on thefeature bottom must be substantially greater than the rate of growth onthe rest of areas, and even more so than in conventional superfilling oflarger interconnects.

In addition to superfilling and overplating issues, micro-defects mayform when electrodepositing Cu for filling interconnect features. Onedefect that can occur is the formation of internal voids inside thefeatures. As Cu is deposited on the feature side walls and top entry ofthe feature, deposition on the side walls and entrance to the featurecan pinch off and thereby close access to the depths of the featureespecially with features which are small (e.g., <100 nm) and/or whichhave a high aspect ratio (depth:width) if the bottom-up growth rate isnot fast enough. Smaller feature size or higher aspect ratio generallyrequires faster bottom-up speed to avoid pinching off. Moreover, smallersize or higher aspect ratio features tend to have thinner seed coverageon the sidewall and bottom of a via/trench where voids can also beproduced due to insufficient copper growth in these areas. An internalvoid can interfere with electrical connectivity through the feature.

Microvoids are another type of defect which can form during or afterelectrolytic Cu deposition due to uneven Cu growth or grainrecrystallization that happens after Cu plating.

In a different aspect, some local areas of a semiconductor substrate,typically areas where there is a Cu seed layer deposited by physicalvapor deposition, may not grow Cu during the electrolytic deposition,resulting in pits or missing metal defects. These Cu voids areconsidered to be “killer defects,” as they reduce the yield ofsemiconductor manufacturing products. Multiple mechanisms contribute tothe formation of these Cu voids, including the semiconductor substrateitself. However, Cu electroplating chemistry has influence on theoccurrence and population of these defects.

Other defects are surface protrusions, which are isolated depositionpeaks occurring at localized high current density sites, localizedimpurity sites, or otherwise. Copper plating chemistry has influence onthe occurrence of such protrusion defects. Although not considered asdefects, Cu surface roughness is also important for semiconductor wafermanufacturing. Generally, a bright Cu surface is desired as it canreduce the swirl patterns formed during wafer entry in the platingsolution. Roughness of Cu deposits makes it more difficult to detectdefects by inspection, as defects may be concealed by peaks and valleysof rough surface topography. Moreover, smooth growth of Cu is becomingmore important for flawlessly filling of fine interconnect structures asthe roughness can cause pinch off of feature and thereby close access tothe depths of the feature. It is generally recognized that Cu platingchemistry, including suppressor, accelerator, and leveler, has greatinfluence on the roughness of Cu deposits.

SUMMARY OF THE INVENTION

The invention is directed to an electrolytic plating composition forelectrolytically plating Cu onto a semiconductor integrated circuitsubstrate having a planar plating surface and submicron-sizedinterconnect features by immersion of the semiconductor integratedcircuit substrate into the electrolytic solution. The compositioncomprises a source of Cu ions in an amount sufficient toelectrolytically deposit Cu onto the substrate and into the electricalinterconnect features and a suppressor compound comprising a combinationof propylene oxide (PO) repeat units and ethylene oxide (EO) repeatunits present in a PO:EO ratio between about 1:9 and about 9:1 andbonded to a nitrogen-containing species, wherein the molecular weight ofthe suppressor compound is between about 1000 and about 30,000.

In another aspect the invention is directed to a method forelectrolytically plating Cu onto a substrate employing the foregoingcomposition.

In another aspect the invention is directed to a method forelectroplating a copper deposit onto a semiconductor integrated circuitdevice substrate with electrical interconnect features includingsubmicron-sized features having bottoms, sidewalls, and top openings,the method comprising immersing the semiconductor integrated circuitdevice substrate into the electrolytic plating composition comprising asource of Cu ions in an amount sufficient to electrolytically deposit Cuonto the substrate and into the electrical interconnect features, anaccelerator, and a suppressor; and supplying electrical current to theelectrolytic composition to deposit Cu onto the substrate and superfillthe submicron-sized features by rapid bottom-up deposition at a verticalCu deposition growth rate in features from the bottoms of the featuresto the top openings of the features which is greater than 50% fasterthan a comparable vertical Cu deposition growth rate of comparableprocess which is equivalent in all respects except that it employs acommercially available suppressor.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph comparing the fill speeds of electrolytic platingbaths comprising a suppressor compound of the present invention (

) against the fill speed of an electrolytic plating bath comprising acommercially available suppressor compound (

). The electrolytic plating bath comprising the suppressor compound ofthe present invention comprises the bath components listed in Example 1and was plated according to the method of Example 7. The electrolyticplating bath comprising the commercially available suppressor compoundcomprises the bath components listed in Comparative Example 1 and wasplated according to the method of Example 7.

FIGS. 2A and 2B are SEM images showing superfilled test trenchesprepared according to the method of Example 7. The trenches in FIG. 2Awere filled using an electrolytic plating bath comprising the additiveslisted in Example 1, including a suppressor compound of the presentinvention. The trenches in FIG. 2B were filled using an electrolyticplating bath comprising the additives listed in Comparative Example 1,including a commercially available suppressor compound.

FIGS. 3A and 3B are SEM images showing superfilled test trenchesprepared according to the method of Example 8. The trenches in FIG. 3Awere filled using an electrolytic plating bath comprising the additiveslisted in Example 5, including a suppressor compound of the presentinvention. The trenches in FIG. 3B were filled using an electrolyticplating bath comprising the additives listed in Comparative Example 5,including a commercially available suppressor compound.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with this invention, compositions are provided suitablefor plating semiconductor integrated circuit substrates havingchallenging fill characteristics, such as interconnect features that arepoorly seeded or not substantially seeded, interconnect features havinga complex geometry, and large diameter interconnect features as well assmall diameter features (less than about 0.5 μm), and features with highaspect ratios (at least about 3:1) or low aspect ratios (less than about3:1) where Cu must fill all the features completely and substantiallydefect-free.

The compositions for Cu superfilling of semiconductor integrated circuitsubstrates having challenging fill characteristics of the presentinvention comprise a suppressor compound and a source of Cu ions. Thesecompositions also typically comprise a leveler, an accelerator, andchloride. The above-listed additives find application in high Cumetal/low acid electrolytic plating baths, in low Cu metal/high acidelectrolytic plating baths, and in mid acid/high Cu metal electrolyticplating baths. The compositions can also comprise other additives whichare known in the art such as halides, grain refiners, quaternary amines,polysulfide compounds, and others. Compositions comprising thesuppressor, leveler, and accelerator of the present invention can beused to fill small diameter/high aspect ratio features.

Preferred suppressors for the Cu plating compositions of the presentinvention comprise polyether groups covalently bonded to a cationicspecies. The cationic polyether suppressor preferably comprises anitrogen atom. Exemplary cationic species comprising a nitrogen atominclude primary, secondary, tertiary, and quaternary amines. By“cationic,” it is meant that the polyether suppressor either contains orcan contain a positive charge in solution. Primary, secondary, andtertiary amines are weakly basic and become protonated and positivelycharged when added to a solution comprising an acid. Quaternary aminescomprise four nitrogen-substituents, and a quaternized nitrogenpossesses a positive charge regardless of the solution pH. The primary,secondary, tertiary, and quaternary amines can be substituted orunsubstituted alkyl amines, substituted or unsubstituted cycloalkylamines, substituted or unsubstituted aromatic amines, substituted orunsubstituted heteroaryl amines, substituted or unsubstituted alkyletheramines, and substituted or unsubstituted aromatic alkyl amines.

The suppressors comprising polyether groups covalently bonded to acationic species preferably comprise at least one amine functionalgroup, preferably between two amine functional groups and five aminefunctional groups. Accordingly, the cationic species can be an amine, adiamine, a triamine, a tetraamine, a pentaamine, or an even higheramine. The alkyl group of the alkylamine can be a substituted orunsubstituted alkyl, preferably a short chain hydrocarbon having between1 and 8 carbons, which may be branched or straight chained. Exemplaryalkylamines can include methylamine, ethylamine, propylamine,n-butylamine, isobutylamine, t-butylamine, ethylenediamine,diethylenetriamine, 1,3-diaminopropane, 1,4-diaminobutane,2-butene-1,4-diamine, and others. The cycloalkyl group of the cycloalkylamine typically comprises a 5- or 6-carbon ring, although bicylic,tricylic, and higher multi-cyclic alkyl amines are applicable. Exemplarycycloalkyl amines include substituted or unsubstitutedcyclopentylamines, cyclohexylamines, cyclopentylamines,cyclopentyldiamines, cyclohexylamines, cyclopentylamines,cylcoalkyltriamines, and higher cycloalkyl amines. Alkylether aminespreferably comprise an ether moiety defined by short chain hydrocarbonstypically having between 1 and 8 carbons, such as diethylene glycoldiamine and triethylene glycol diamine.

The polyethers comprise a chain of repeat units, wherein the chain ofrepeat units can be formed by the polymerization of epoxide monomers. Ina preferred embodiment, the epoxide monomers are selected from ethyleneoxide monomer, propylene oxide monomer, and a combination thereof.Preferably, the polyether comprises a chain of repeat units formed bythe polymerization of both ethylene oxide monomer and propylene oxidemonomer. Accordingly, the ratio of ethylene oxide (EO) repeat units andpropylene oxide (PO) repeat units in the polyether can be between about1:9 and about 9:1. In one embodiment, the ratio is between about 2:3 andabout 3:2, such as about 1:1. In one embodiment, the polyether comprisesbetween about 1 and about 30 EO repeat units and between about 30 andabout 1 PO repeat units, such as between about 7 and about 15 EO repeatunits and between about 15 and about 7 PO repeat units. In a currentlypreferred embodiment, the polyether comprises, for example, about 11 EOrepeat units and about 13 PO repeat units. In another preferredembodiment, the polyether comprises about 7 or 8 EO repeat units andabout 9 PO repeat units. Accordingly, the molecular weight of thepolyether can be between as low as about 100 g/mol and as high as about3600 g/mol, preferably between about 1000 g/mol and about 1800 g/mol,and in one embodiment, between about 1200 g/mol and about 1400 g/mol.

The polyether preferably comprises EO repeat units and PO repeat unitsin random, alternating, or block configurations. In a randomconfiguration, the EO repeat units and PO repeat units have nodiscernable linear pattern along the polyether chain. In an alternatingconfiguration, the EO repeat units and PO repeat units alternateaccording to some defined pattern, such as repeating units of EO-PO,PO-EO, and other alternating patterns. The co-polymer can be arranged ina block configuration. In the block configuration, the linear portion ofthe polyether chain comprises a block of EO repeat units bonded to ablock of PO repeat units. The polyether chain may comprise a diblock.That is, the chain may comprise a first block of EO repeat units bondedto a second block of PO repeat units. Alternatively, the chain maycomprise a first block of PO repeat units bonded to a second block of EOrepeat units. In more complicated block configurations, the polyetherchain may comprise a triblock (EO block-PO block-EO block or PO block-EOblock-PO block), tetrablock, pentablock, or higher block arrangements.It has been discovered that a PO block-EO block-PO triblockconfiguration is effective to reduce polyether suppressor foaming inelectrolytic solution. In one embodiment of the block configuration,each block of repeat units comprises between about 1 and about 30 repeatunits, more preferably between about 7 and about 15 repeat units. In apreferred embodiment involving a PO block-EO block-PO block tri-blockconfiguration, the first PO-block bonded to the cationic speciescomprises between about 7 and about 15 PO repeat units, the secondEO-block bonded to the PO-block comprises between about 7 and about 15repeat units, and the third PO-block bonded to the second EO-blockcomprises between about 1 and about 5 repeat units.

Optionally, the PO/ED polyethers are capped by a substituted orunsubstitute alkyl group, aryl group, aralkyl, or heteroalkyl group. Apreferred capping moiety for its ease of manufacture and low cost is amethyl group.

The suppressor compounds comprising polyether groups covalently bondedto a cationic species comprise a positive charge in acidic solution andrepeat units, EO and PO. It is thought that the separate functionalitiesof the positive charge, the EO repeat units, and the PO repeat unitscontribute different chemical and physical properties which affect, andthereby enhance, the function of the polyether as a suppressor in the Cuplating compositions of the present invention. Without being bound to aparticular theory, it is thought that the positive charge of thecationic species enhances the attraction of the suppressor compound toCu deposited into interconnect features, which, during an electrolyticplating operation, functions as the cathode. It is believed that the POrepeat unit is the active repeat unit in the suppressors of the presentinvention. That is, the PO repeat unit has suppressor functionality andaffects the quality of the Cu deposit. Without being bound to aparticular theory, it is thought that the PO repeat units, beingrelatively hydrophobic form a polarizing film over a Cu seed layer andelectrolytically deposited Cu.

A Cu seed layer is typically deposited over the barrier layer ininterconnect features by CVD, PVD, and other methods known in the art.The Cu seed layer acts as the cathode for further reduction of Cu thatsuperfills the interconnects during the electrolytic plating operation.Cu seed layers can be thin, i.e., less than about 700 Angstroms. Or theymay be thick, i.e., between about 700 Angstroms and about 1500Angstroms. However, the copper thickness on the bottom or sidewall offeatures is typically much thinner than those on the feature top andunpatterned areas due to the non-uniform deposition rates of PVDprocesses. In some extreme circumstances, the copper coverage on thebottom or sidewall could be so thin that the seed is discontinuous.Accordingly, in some instances the substrate comprises surface portionswhich have a Cu seed thereon which is less than about 700 angstromsthick, and in some instances the seed is discontinuous. In another case,the seed coverage on the top of features is thicker than on otherfeature areas, which is often called “seed overhang.” Generally, theuniformity of seed coverage degrades significantly with shrinkingfeature size and increasing aspect ratio. The present invention has beenshown to perform well, and better than the prior art, with thin oroverhanged seed layers.

The suppressor compound with somewhat hydrophobic PO repeat unitscovalently bonded to a nitrogen-containing cationic species is able toform a suppressive film over the Cu seed layer. In the case of thincopper seed coverage, this polarizing organic film will cause thecurrent to be more evenly distributed over the entire interconnectfeature, i.e., the bottom and sidewalls of the via or trench. Evencurrent distribution is believed to promote faster bottom up growthrelative to sidewall growth, and may also reduce or eliminate bottom andsidewall voiding. This strongly suppressive suppressor is also desirableto suppress copper growth at the seed overhang areas on the top of theinterconnect features, reducing the formation of internal voids fromearly pinching off. It has been discovered that the suppressor compoundcomprising a polyether group covalently bonded to a cationic species ofthe present invention is effective at suppressing Cu deposition overthin or thick Cu seed layers. A polyether constituted only of PO repeatunits, being relatively hydrophobic, lacks the solubility necessary toact as an adequate suppressor. That is, while PO is a superiorsuppressor, a polymer constituted only of PO repeat units may not besoluble enough to go into the Cu plating solution so that it can adsorbonto the Cu seed layer in a high enough concentration to form apolarizing film. Accordingly, the polyether group further comprises EOrepeat units to enhance its hydrophilicity and thus its solubility.

In those embodiments where the cationic species comprises a nitrogenatom, the nitrogen atom can be covalently bonded to one, two, or threePO/EO polyethers. Preferably, the nitrogen atom is covalently bonded totwo PO/EO polyethers. In embodiments where the cationic species is aprimary, secondary, or tertiary amine, the nitrogen atom can bealkylated to quaternize the nitrogen atom and render it positivelycharged. Preferably, the alkyl group is a short chain hydrocarbonradical having between 1 and 8 carbons, such as methyl, ethyl, n-propyl,isopropyl, and the like. Preferably the alkyl group is a methyl group.Accordingly, the nitrogen atom can form a quaternary amine having apositive charge where the suppressor comprises, for example, two PO/EOpolyethers covalently bonded to a methylated alkylamine.

In those embodiments where the cationic species comprises a nitrogenatom, the cationic species can have any of the following structures (1),(2), (3), or (4):

wherein

R₁ is a substituted or unsubstituted alkyl group, preferably a straightchained or branched alkyl group having between 1 and 8 carbons, andpreferably, R₁ is substituted with another amino group to which apolyether group is covalently bonded, the polyether group comprising EOrepeat units, PO repeat units, or a combination thereof arranged inrandom, alternating, or block configurations,

R₂ is selected from the group consisting of hydrogen and alkyl group,and where R₂ is an alkyl group, it is preferably a methyl group,

R₃ is a polyether group preferably comprising EO repeat units, PO repeatunits, or a combination thereof arranged in random, alternating, orblock configurations, and

R₄ is selected from the group consisting of hydrogen, substituted orunsubstituted alkyl group, aryl group, aralkyl, or heteroaryl group.

The suppressor compounds of the invention have a molecular weightbetween about 1000 and about 30,000. Exemplary suppressor compoundscomprising a polyether group covalently bonded to a cationic specieswherein the polyether is covalently bonded to a nitrogen atom are shownby structures (5), (6), (7), (8), and (9) below.

Structure (5) is a PO/EO block copolymer of ethylenediamine having thestructure:

and wherein n can be between 1 and about 30 and m can be between 1 andabout 30. Accordingly a suppressor compound having the structure (5)comprises between about 4 and about 120 total PO repeat units andbetween about 4 and about 120 total EO repeat units on the four PO/EOblock copolymers. The molecular weight of the PO (hydrophobic unit)block on a single PO/EO block copolymer can be between about 50 g/moland about 1800 g/mol, and the molecular weight of the EO (hydrophilicunit) block on a single PO/EO block copolymer can be between about 40g/mol and about 1400 g/mol. The molecular weight of a single PO/EOcopolymer can be between about 100 g/mol about 3600 g/mol. An exemplarysuppressor compound having the structure (5) is available from BASFCorporation of Mt. Olive, N.J. under the trade designation Tetronic®704. This suppressor compound comprises about 13 PO repeat units perPO/EO block copolymer for a total of about 52 PO repeat units on allfour PO/EO block copolymers and about 11 EO repeat units per PO/EO blockcopolymer for a total of about 44 EO repeat units on all four PO/EOblock copolymers. Accordingly, the total MW of Tetronic® 704 is betweenabout 5000 g/mol and about 5500 g/mol. Another exemplary block copolymerof structure (5) is also available from BASF Corporation under the tradedesignation Tetronic® 504. This suppressor compound comprises about 9 POrepeat units per PO/EO block copolymer for a total of about 36 PO repeatunits on all four PO/EO block copolymers and about 7.5 EO repeat unitsper PO/EO block copolymer for a total of about 30 EO repeat units on allfour PO/EO block copolymers. Accordingly, the total MW of Tetronic® 504is between about 3200 g/mol and about 3600 g/mol. The bath compositioncan comprise a mixture of block copolymers of structure (5).

Structure (6) is an N-methylated PO/EO block copolymer ofethylenediamine having the general structure:

wherein n can be between 1 and about 30 and m can be between 1 and about30. A source of the suppressor compound having structure (6) isN-methylated Tetronic® 504 or N-methylated Tetronic® 704.

Structure (7) is a methyl-capped PO/EO block copolymer ofethylenediamine having the general structure:

and wherein n can be between 1 and about 30 and m can be between 1 andabout 30. A source of the suppressor compound having structure (7) ismethyl-capped Tetronic® 504 or methyl-capped Tetronic® 704. In variousalternatives, one of the terminal oxygen atoms can be bonded to a methylgroup and the other three terminal oxygen atoms can be bonded to ahydrogen atom; or two of the terminal oxygen atoms can be bonded to amethyl group and two of the terminal oxygen atoms can be bonded to ahydrogen atom; or three of the terminal oxygen atoms can be bonded to amethyl group and one of the terminal oxygen atoms can be bonded to ahydrogen atom; or all of the terminal oxygen atoms can be bonded to amethyl group.

In yet another alternative, the block copolymer is methylated and cappedas described above, as long as the cloud point is such that it iscompatible with copper solution.

Structure (8) is a PO/EO/PO tri-block copolymer of ethylenediaminehaving the general structure:

and wherein n can be between 1 and about 30, m can be between 1 andabout 30, and o can be between about 1 and about 5, or such that thecloud point is compatible with copper solution. Preferably, o is 1 or 2.A source of a suppressor compound having structure (8) is PO-cappedTetronic® 504 or PO-capped Tetronic® 704.

Structure (9) is a PO/EO block copolymer of triethylene glycol diaminehaving the structure:

and wherein n can be between 1 and about 30 and m can be between 1 andabout 30. Triethylene glycol diamine, to which the PO/EO blockco-polymers can be covalently bonded, is available from Huntsman LLC ofSalt Lake City, Utah under the trade designation Jeffamine XTJ-504. Thestructure of the PO/EO block copolymer in suppressor compounds havingstructure (9) can be substantially the same as the PO/EO blockcopolymers in Tetronic® 504 and Tetronic® 704. Accordingly, the MW of asuppressor compound having structure (9) can be between about 5200 g/moland about 5800 g/mol.

The suppressor compounds described above can be present in an overallbath concentration between about 10 mg/L to about 1000 mg/L, preferablybetween about 50 mg/L to about 200 mg/L. Adding the weakly cationicpolyether suppressors to Cu plating compositions within theseconcentration ranges is sufficient to fill complex features in anintegrated circuit device, with the added benefits of reducing earlypinching off, bottom voiding, or sidewall voiding.

The composition of the invention also preferably includes a levelerwhich has an enhanced leveling effect without substantially interferingwith superfilling of Cu into high aspect ratio features. One suchpreferred leveler is disclosed in U.S. Pat. Pub. No. 2005/0045488, filedOct. 12, 2004, the entire disclosure of which is expressly incorporatedby reference. This leveler does not substantially interfere withsuperfilling, so the Cu bath can be formulated with a combination ofaccelerator and suppressor additives which provides a rate of growth inthe vertical direction which is substantially greater than the rate ofgrowth in the horizontal direction, and even more so than inconventional superfilling of larger interconnects. One such preferredleveler is a reaction product of 4-vinyl pyridine and methyl sulfateavailable from Enthone Inc. under the trade name ViaForm L700. Theleveler is incorporated, for example, in a concentration between about0.1 mg/L and about 25 mg/L.

With regard to accelerators, in a system currently preferred by theapplicants, the accelerators are bath soluble organic divalent sulfurcompounds as disclosed in U.S. Pat. No. 6,776,893, the entire disclosureof which is expressly incorporated by reference. In one preferredembodiment, the accelerator corresponds to the formula (10)R₁—(S)_(n)RXO₃M  (10),wherein

M is hydrogen, alkali metal or ammonium as needed to satisfy thevalence;

X is S or P;

R is an alkylene or cyclic alkylene group of 1 to 8 carbon atoms, anaromatic hydrocarbon or an aliphatic aromatic hydrocarbon of 6 to 12carbon atoms;

n is 1 to 6; and

R₁ is MO₃XR wherein M, X and R are as defined above.

An accelerator which is especially preferred is 1-propanesulfonic acid,3,3′-dithiobis, disodium salt according to the following formula (11):

The accelerator is incorporated typically in a concentration betweenabout 0.5 and about 1000 mg/L, more typically between about 2 and about50 mg/L, such as between about 5 and 30 mg/L. A significant aspect ofthe current invention is that it permits the use of a greaterconcentration of accelerator, and in many applications in fact it mustbe used in conjunction with a greater concentration of accelerator thanin conventional processes. This permits achieving the enhanced rates ofsuperfilling demonstrated in Example 7 below.

Optionally, additional leveling compounds of the following types can beincorporated into the bath such as the reaction product of benzylchloride and hydroxyethyl polyethylenimine as disclosed in U.S. Pat.Pub. No. 2003/0168343, the entire disclosure of which is expresslyincorporated herein by reference.

The components of the Cu electrolytic plating bath may vary widelydepending on the substrate to be plated and the type of Cu depositdesired. The electrolytic baths include acid baths and alkaline baths. Avariety of Cu electrolytic plating baths are described in the bookentitled Modern Electroplating, edited by F. A. Lowenheim, John Reily &Sons, Inc., 1974, pages 183-203. Exemplary Cu electrolytic plating bathsinclude Cu fluoroborate, Cu pyrophosphate, Cu cyanide, Cu phosphonate,and other Cu metal complexes such as methane sulfonic acid. The mosttypical Cu electrolytic plating bath comprises Cu sulfate in an acidsolution.

The concentration of Cu and acid may vary over wide limits; for example,from about 4 to about 70 g/L Cu and from about 2 to about 225 g/L acid.In this regard the compounds of the invention are suitable for use inall acid/Cu concentration ranges, such as high acid/low Cu systems, inlow acid/high Cu systems, and mid acid/high Cu systems. In high acid/lowCu systems, the Cu ion concentration can be on the order of 4 g/L to onthe order of 30 g/L; and the acid concentration may be sulfuric acid inan amount of greater than about 100 g/L up to about 225 g/L. In one highacid/low Cu system, the Cu ion concentration is about 17 g/L where theH₂SO₄ concentration is about 180 g/L. In low acid/high Cu systems, theCu ion concentration can be on the order of greater than about 30 g/L,40 g/L, and even up to on the order of 60 g/L Cu (50 g/L Cu correspondsto 200 g/L CuSO₄.5H₂O Cu sulfate pentahydrate). The acid concentrationin these systems is less than 50 g/L, 40 g/L, and even 30 g/L H₂SO₄,down to about 2 g/L. In one exemplary low acid/high Cu system, the Cuconcentration is about 40 g/L and the H₂SO₄ concentration is about 10g/L. In mid acid/high Cu systems, the Cu ion concentration can be on theorder of 30 g/L to on the order of 60 g/L; and the acid concentrationmay be sulfuric acid in an amount of greater than about 50 g/L up toabout 100 g/L. In one mid acid/high Cu system, the Cu ion concentrationis about 50 g/L where the H₂SO₄ concentration is about 80 g/L.

Chloride ion may also be used in the bath at a level up to 200 mg/L,preferably about 10 to 90 mg/L. Chloride ion is added in theseconcentration ranges to enhance the function of other bath additives.These additives system include accelerators, suppressors, and levelers.

A large variety of additives may typically be used in the bath toprovide desired surface finishes for the Cu plated metal. Usually morethan one additive is used with each additive forming a desired function.At least two additives are generally used to initiate bottom-up fillingof interconnect features as well as for improved metal plated physical(such as brightness), structural, and electrical properties (such aselectrical conductivity and reliability). Particular additives (usuallyorganic additives) are used for grain refinement, suppression ofdendritic growth, and improved covering and throwing power. Typicaladditives used in electrolytic plating are discussed in a number ofreferences including Modern Electroplating, cited above. A particularlydesirable additive system uses a mixture of aromatic or aliphaticquaternary amines, polysulfide compounds, and polyethers. Otheradditives include items such as selenium, tellurium, and sulfurcompounds.

Plating equipment for plating semiconductor substrates are well knownand are described in, for example, Haydu et al. U.S. Pat. No. 6,024,856.Plating equipment comprises an electrolytic plating tank which holds Cuelectrolytic solution and which is made of a suitable material such asplastic or other material inert to the electrolytic plating solution.The tank may be cylindrical, especially for wafer plating. A cathode ishorizontally disposed at the upper part of tank and may be any typesubstrate such as a silicon wafer having openings such as trenches andvias. The wafer substrate is typically coated first with a barrierlayer, which may be titanium nitride, tantalum, tantalum nitride, orruthenium to inhibit Cu diffusion and next with a seed layer of Cu orother metal to initiate Cu superfilling plating thereon. A Cu seed layermay be applied by chemical vapor deposition (CVD), physical vapordeposition (PVD), or the like. An anode is also preferably circular forwafer plating and is horizontally disposed at the lower part of tankforming a space between the anode and cathode. The anode is typically asoluble anode such as copper metal.

The bath additives are useful in combination with membrane technologybeing developed by various tool manufacturers. In this system, the anodemay be isolated from the organic bath additives by a membrane. Thepurpose of the separation of the anode and the organic bath additives isto minimize the oxidation of the organic bath additives on the anodesurface.

The cathode substrate and anode are electrically connected by wiringand, respectively, to a rectifier (power supply). The cathode substratefor direct or pulse current has a net negative charge so that Cu ions inthe solution are reduced at the cathode substrate forming plated Cumetal on the cathode surface. An oxidation reaction takes place at theanode. The cathode and anode may be horizontally or vertically disposedin the tank.

During operation of the electrolytic plating system, Cu metal is platedon the surface of a cathode substrate when the rectifier is energized. Apulse current, direct current, reverse periodic current, or othersuitable current may be employed. The temperature of the electrolyticsolution may be maintained using a heater/cooler whereby electrolyticsolution is removed from the holding tank and flows through theheater/cooler and then is recycled to the holding tank.

In the case of thin copper seed coverage, less current will be deliveredto the lower portions of interconnect features, which may lead to bottomor sidewall voids and slow bottom-up growth. For features which haveseed overhang, the electrolytic copper growth may have early pinchingoff on the feature tops before the bottom-up growth can reach thesurface. Conventional suppressors may not distribute enough current tothe bottom of the interconnect feature to promote bottom-up superfillingrapid enough to prevent the pinching off of interconnect features by Cuelectrolytic deposition leading to the formation of internal voids,especially for features seeded with a thin Cu seed layer. Also,conventional suppressors may not have strong enough suppression tosuppress copper growth on seed overhang areas to prevent early pinchingoff. Without being bound to a particular theory, it is thought that thesuppressor compounds of the present invention function to inhibit theformation of internal voids and enhance the bottom-up superfillingdeposition rate by up to twice the rate over a typical electrolyticplating solution not comprising the suppressor compounds of the presentinvention by forming a polarizing film over the Cu seed layer. Also, thesuppressor compounds of the present invention possess strongersuppression (more polarizing) than most conventional suppressors, whichallows the current to be distributed more evenly over the Cu seed layerdeposited on the bottom and sidewalls of the interconnect featureleading to the reduction or elimination of bottom and sidewall voids. Aneven current distribution enhances Cu growth at the bottom of thefeature relative to deposition at other regions to such an extent thatbottom-up superfilling occurs so rapidly that deposition at the side andtop of the feature will not cause a pinching off of the deposit and theformation of internal voids. The suppressor compounds of the presentinvention are effective at rapid bottom-up superfilling over thin oroverhanged Cu seed layers. For example, the suppressor compounds havebeen found effective to superfill an interconnect feature seeded with athin Cu seed layer on the bottom and side walls of an interconnectfeature having a thickness between about 1 Angstrom and about 100Angstroms.

An advantage of adding the suppressor compounds of the present inventionto electrolytic Cu plating solutions is the reduction in the occurrenceof internal voids as compared to deposits formed from a bath notcontaining these compounds. Internal voids form from Cu depositing onthe feature side walls and top entry of the feature, which causespinching off and thereby closes access to the depths of the feature.This defect is observed especially with features which are small (e.g.,<100 nm) and/or which have a high aspect ratio (depth:width), forexample, >4:1. Those voids left in the feature can interfere withelectrical connectivity of copper interconnects. The suppressorcompounds of the invention appear to reduce the incidence of internalvoids by the above-described rapid superfilling mechanism and strongsuppression.

It is an optional feature of the process that the plating system becontrolled as described in U.S. Pat. No. 6,024,856 by removing a portionof the electrolytic solution from the system when a predeterminedoperating parameter (condition) is met and new electrolytic solution isadded to the system either simultaneously or after the removal insubstantially the same amount. The new electrolytic solution ispreferably a single liquid containing all the materials needed tomaintain the electrolytic plating bath and system. The addition/removalsystem maintains a steady-state constant plating system having enhancedplating effects such as constant plating properties. With this systemand method the plating bath reaches a steady state where bath componentsare substantially a steady-state value.

Electrolysis conditions such as electric current concentration, appliedvoltage, electric current density, and electrolytic solution temperatureare essentially the same as those in conventional electrolytic Cuplating methods. For example, the bath temperature is typically aboutroom temperature such as about 20-27° C., but may be at elevatedtemperatures up to about 40° C. or higher. The electrical currentdensity is typically up to about 100 mA/cm², typically about 2 mA/cm² toabout 60 mA/cm². It is preferred to use an anode to cathode ratio ofabout 1:1, but this may also vary widely from about 1:4 to 4:1. Theprocess also uses mixing in the electrolytic plating tank which may besupplied by agitation or preferably by the circulating flow of recycleelectrolytic solution through the tank. The flow through theelectrolytic plating tank provides a typical residence time ofelectrolytic solution in the tank of less than about 1 minute, moretypically less than 30 seconds, e.g., 10-20 seconds.

The following examples further illustrate the practice of the presentinvention.

EXAMPLES Example 1 Low Acid/High Cu Superfill Electrolytic Plating Bathwith Suppressor of the Invention

To superfill a small diameter/high aspect ratio integrated circuitdevice feature, a Low acid/High Cu electrolytic plating bath wasprepared comprising the following components:

-   -   160 g/L CuSO₄.5H₂O (copper sulfate pentahydrate)    -   10 g/L H₂SO₄ (concentrated sulfuric acid)    -   50 mg/L Chloride ion    -   9 mL/L ViaForm® Accelerator    -   200 mg/L of Cationic Suppressor (PO/EO block copolymer of        ethylenediamine having a MW of 5500 g/mol corresponding to        structure (5)).

The bath (1 L) was prepared as follows. CuSO₄.5H₂O (160 g) was fullydissolved in deionized water. Concentrated sulfuric acid (10 g) wasadded followed by addition of hydrochloric acid sufficient to yield 50mg chloride ion in solution. Deionized water was added for a totalvolume of 1 liter. The final plating bath was prepared by furtheraddition of ViaForm Accelerator (9 mL) and PO/EO block copolymer ofethylenediamine having a MW of 5500 g/mol corresponding to structure (5)(200 mg).

Comparative Example 1 Low Acid/High Cu Superfill Electrolytic PlatingBath with Comparative Suppressor

A comparative Low acid/High Cu electrolytic plating bath was preparedcomprising the following components:

-   -   160 g/L CuSO₄.5H₂O (copper sulfate pentahydrate)    -   10 g/L H₂SO₄ (concentrated sulfuric acid)    -   50 mg/L Chloride ion    -   9 mL/L ViaForm® Accelerator    -   200 mg/L Commercially Available Suppressor having the following        formula:        wherein the sum of e+f+g=21 and the sum of h+i+j=27, available        from Enthone Inc. under the tradename ViaForm.

Example 2 High Acid/Low Cu Superfill Electrolytic Plating Bath withSuppressor of the Invention

To superfill a small diameter/high aspect ratio integrated circuitdevice feature, a High Acid/Low Cu electrolytic plating bath wasprepared comprising the following components:

-   -   70 g/L CuSO₄.5H₂O (copper sulfate pentahydrate)    -   180 g/L H₂SO₄ (concentrated sulfuric acid)    -   50 mg/L Chloride ion    -   3 mL/L ViaForm® Accelerator    -   400 mg/L Cationic Suppressor (PO/EO block copolymer of        ethylenediamine having a MW of 5500 g/mol corresponding to        structure (5)).

Example 3 Mid Acid/High Cu Superfill Electrolytic Plating Bath withSuppressor of the Invention

To superfill a small diameter/low aspect ratio integrated circuit devicefeature, a Mid acid/High Cu electrolytic plating bath was preparedcomprising the following components:

-   -   200 g/L CuSO₄.5H₂O (copper sulfate pentahydrate)    -   80 g/L H₂SO₄ (concentrated sulfuric acid)    -   50 mg/L Chloride ion    -   8 mL/L ViaForm® Accelerator    -   200 mg/L Cationic Suppressor (PO/EO block copolymer of        ethylenediamine having a MW of 5500 g/mol corresponding to        structure (5))    -   4 mL/L ViaForm® L700.

Example 4 Low Acid/High Cu Superfill Electrolytic Plating Bath withSuppressor of the Invention

To superfill a small diameter/high aspect ratio integrated circuitdevice feature, a High Acid/Low Cu electrolytic plating bath wasprepared comprising the following components:

-   -   160 g/L CuSO₄.5H₂O (copper sulfate pentahydrate)    -   10 g/L H₂SO₄ (concentrated sulfuric acid)    -   50 mg/L Chloride ion    -   18 mg/L 1-propanesulfonic acid, 3,3′-dithiobis, disodium salt    -   200 mg/L Cationic Suppressor (PO/EO block copolymer of        triethylene glycol diamine having a MW of 5700 g/mol        corresponding to structure (9))    -   2 mL/L ViaForm® L700.

Example 5 Low Acid/High Cu Superfill Electrolytic Plating Bath withSuppressor of the Invention

A comparative Low acid/High Cu electrolytic plating bath was preparedcomprising the following components:

-   -   160 g/L CuSO₄.5H₂O (copper sulfate pentahydrate)    -   10 g/L H₂SO₄ (concentrated sulfuric acid)    -   50 mg/L Chloride ion    -   9 mL/L ViaForm Accelerator    -   200 mg/L Cationic Suppressor (PO/EO block copolymer of        ethylenediamine having a MW of 3400 g/mol corresponding to        structure (5)).

Comparative Example 5 Low Acid/High Cu Superfill Electrolytic PlatingBath with Comparative Suppressor

To superfill a small diameter/high aspect ratio integrated circuitdevice feature, a Low acid/High Cu electrolytic plating bath wasprepared comprising the following components:

-   -   160 g/L CuSO₄.5H₂O (copper sulfate pentahydrate)    -   10 g/L H₂SO₄ (concentrated sulfuric acid)    -   50 mg/L Chloride ion    -   9 mL/L ViaForm® Accelerator    -   200 mg/L Commercially Available Suppressor of Example 1.

Example 6 Low Acid/High Cu Superfill Electrolytic Plating Bath withSuppressor of the Invention

To superfill a small diameter/high aspect ratio integrated circuitdevice feature, a Low acid/High Cu electrolytic plating bath wasprepared comprising the following components:

-   -   160 g/L CuSO₄.5H₂O (copper sulfate pentahydrate)    -   10 g/L H₂SO₄ (concentrated sulfuric acid)    -   50 mg/L Chloride ion    -   9 mL/L ViaForm® Accelerator    -   200 mg/L Cationic Suppressor (PO/EO/PO block copolymer of        triethylene glycol diamine having a MW of 5600 g/mol        corresponding to structure (8)).

Example 7 Superfilling Test Trenches with Low Acid/High Cu SuperfillElectrolytic Plating Bath

Test trenches (140 nm; aspect ratio between 3 and 4:1)) were superfilledwith Cu using the low acid/high Cu electrolytic plating bath of Example1 comprising a cationic suppressor of the invention and compared to testtrenches superfilled with Cu using the low acid/high Cu electrolyticplating bath of Comparative Example 1 comprising a commerciallyavailable suppressor.

The test trenches superfilled with the bath of Example 1 filled faster(i.e., more growth on the bottom) as compared to the test trenchessuperfilled with the conventional electrolytic plating bath ofComparative Example 1. FIG. 1 is a graph showing the plating speedsachieved with the bath of Example 1 (

) compared to the plating speeds achieved with the bath of ComparativeExample 1 (

). In both cases, the Cu was deposited at a current density of 7 mA/cm²for 0 to 6 seconds to compare bottom growth speeds. This illustratesthat rapid bottom-up deposition is achieved at a superfill speed bywhich Cu deposition in a vertical direction from the bottoms of thefeatures to the top openings of the features is greater than 15 timesfaster and even greater than 20 times faster than Cu deposition onplanar surfaces outside the features. That is, for example, the verticalgrowth rate for the invention is about 3600 angstroms in six seconds, or600 angstroms per second; while the field thickness growth rate is about150 angstroms in six seconds, or about 25 angstroms per second. So inthis example the vertical growth rate is 24 times the field thicknessgrowth rate (600 v. 25 angstroms/sec). The vertical growth rate for thecomparative process is about 1500 angstroms in six seconds, or 250angstroms per second; while the field thickness growth rate is about 150angstroms in six seconds, or about 25 angstroms per second (250 v. 25angstroms/sec). This corresponds to a comparative vertical growth rateof about 10 times the field thickness growth rate. The foregoingdeposition growth rates are calculated over the first six seconds ofdeposition. These data also reveal that the process of the inventionachieves a rate of vertical growth in the features which is 1.5 times,or 50%, (e.g., between 1.5 and 3 times) greater than processescomparable in all respects except that they employ the statedcommercially available suppressor. “Vertical” in this respect refers tothe orientation of the growth with respect to the feature opening andfeature bottom, and does not refer to any particular orientation of thesubstrate with respect to the deposition tank.

It was also observed that the plating bath of Example 1 deposited Cu onextremely thin or discontinuous seed with significantly less bottom andsidewall voiding as compared to plating with the bath of ComparativeExample 1. See FIGS. 2A and 2B, which are SEM image of test vias platedwith the bath of Example 1 (FIG. 2A) and the bath of Comparative Example1 (FIG. 2B). Electrolytic deposition occurred at a current density of 10mA/cm². It can be observed that electrolytic plating using the bath ofExample 1 resulted in significantly less bottom and sidewall voiding ascompared to electrolytic plating using the bath of Comparative Example1.

Example 8 Superfilling Test Trenches with Low Acid/High Cu SuperfillElectrolytic Plating Bath

Test trenches were superfilled with Cu using the low acid/high Cuelectrolytic plating bath of Example 5 comprising a cationic suppressorof the invention and compared to test trenches superfilled with Cu usingthe low acid/high Cu electrolytic plating bath of Comparative Example 5comprising a commercially available suppressor. SEM images of theelectrolytically plated Cu deposit in the test trenches are shown inFIGS. 3A and 3B. FIG. 3A is an SEM image of the test trencheselectrolytically plated with the bath of Example 5. FIG. 3B is an SEMimage of the test trenches electrolytically plated with the bath ofComparative Example 5. Both deposits were plated at a current density of7 mA/cm² for 10 seconds to reveal the progression of bottom-up growth.It can be seen from the SEM images that superfilling using the bath ofExample 5 achieved more complete via filling than electrolyticallysuperfilling using the bath of Comparative Example 5.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. Forexample, that the foregoing description and following claims refer to“an” interconnect means that there are one or more such interconnects.The terms “comprising”, “including” and “having” are intended to beinclusive and mean that there may be additional elements other than thelisted elements. As various changes could be made in the above withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description and shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense. The scope of invention is defined by the appended claims andmodifications to the embodiments above may be made that do not departfrom the scope of the invention.

1. An electrolytic plating composition for electrolytically plating Cuonto a semiconductor integrated circuit substrate having a planarplating surface and submicron-sized interconnect features by immersionof the semiconductor integrated circuit substrate into the electrolyticsolution, the composition comprising: a source of Cu ions in an amountsufficient to electrolytically deposit Cu onto the substrate and intothe electrical interconnect features; and a suppressor comprising acompound selected from the group consisting of: (i) a first suppressorcompound comprising a polyether group bonded to a nitrogen-containingspecies, wherein the polyether group comprises a combination ofpropylene oxide (PO) repeat units and ethylene oxide (EO) repeat unitspresent in a PO:EO ratio between about 1:9 and about 9:1, and whereinthe molecular weight of the first suppressor compound is between about1000 and about 3600 g/mol; (ii) a second suppressor compound comprisinga polyether group bonded to a nitrogen-containing species, wherein thepolyether group comprises a combination of propylene oxide (PO) repeatunits and ethylene oxide (EO) repeat units present in a PO:EO ratiobetween about 1:9 and about 9:1, wherein the molecular weight of thesecond suppressor compound is between about 1000 and about 30,000 g/mol,and wherein the second suppressor compound further comprises a cappingmoiety selected from the group consisting of an alkyl group or a blockpolymer comprising propylene oxide repeat units; (iii) a thirdsuppressor compound comprising a polyether group bonded to anitrogen-containing species, wherein the polyether group comprises acombination of propylene oxide (PO) repeat units and ethylene oxide (EO)repeat units present in a PO:EO ratio between about 1:9 and about 9:1,wherein the nitrogen-containing species is an alkylether amine, andwherein the molecular weight of the third suppressor compound is betweenabout 1000 and about 30,000 g/mol; and (iv) a fourth suppressor compoundcomprising a polyether group bonded to a nitrogen-containing species,wherein the polyether group comprises a combination of propylene oxide(PO) repeat units and ethylene oxide (EO) repeat units present in aPO:EO ratio between about 1:9 and about 9:1, wherein the molecularweight of the fourth suppressor compound is between about 1000 and about30,000 g/mol, and wherein a nitrogen in the nitrogen-containing speciesis a quaternary amine; (v) a fifth suppressor compound comprising apolyether group bonded to a nitrogen-containing species, wherein thepolyether group comprises a combination of propylene oxide (PO) repeatunits and ethylene oxide (EO) repeat units present in a PO:EO ratiobetween about 1:9 and about 9:1, wherein the molecular weight of thefifth suppressor compound is between about 1000 and about 30,000 g/mol,and wherein the composition comprises less than about 30 g/L acid whenthe fifth suppressor is selected; (vi) a sixth suppressor compoundcomprising a polyether group bonded to a nitrogen-containing species,wherein the polyether group comprises a combination of propylene oxide(PO) repeat units and ethylene oxide (EO) repeat units present in aPO:EO ratio between about 1:9 and about 9:1, wherein the molecularweight of the sixth suppressor compound is between about 1000 and about30,000 g/mol, and wherein the composition comprises between about 4 g/Land about 30 g/L copper ion when the sixth suppressor is selected; and(vi) combinations thereof.
 2. The electrolytic plating composition ofclaim 1 wherein the propylene oxide repeat units and ethylene oxiderepeat units are present in a PO:EO ratio between about 2:3 and about3:2.
 3. The electrolytic plating composition of claim 1 wherein the EOand PO repeat units are arranged in a block co-polymer sequence.
 4. Theelectrolytic plating composition of claim 2 wherein the EO and PO repeatunits are arranged in a block co-polymer sequence.
 5. The electrolyticplating composition of claim 1 wherein the nitrogen-containing speciescomprises at least one amine functional group.
 6. The electrolyticplating composition of claim 5 wherein the polyether group is bonded toa nitrogen atom in the at least one amine functional group.
 7. Theelectrolytic plating composition of claim 5 wherein the at least oneamine functional group is a quaternary amine.
 8. The electrolyticplating composition of claim 2 wherein the nitrogen-containing speciescomprises at least one amine functional group.
 9. The electrolyticplating composition of claim 7 wherein the polyether group is bonded toa nitrogen atom in the at least one amine functional group.
 10. Theelectrolytic plating composition of claim 8 wherein the at least oneamine functional group is a quaternary amine.
 11. The electrolyticplating composition of claim 1 wherein the nitrogen-containing speciescomprises between two and five amine functional groups.
 12. Theelectrolytic plating composition of claim 2 wherein thenitrogen-containing species comprises between two and five aminefunctional groups.
 13. The electrolytic plating composition of claim 2wherein the nitrogen-containing species comprises a diamine.
 14. Theelectrolytic plating composition of claim 2 wherein thenitrogen-containing species is selected from the group consisting ofethylene diamine and triethylene glycol diamine.
 15. The electrolyticplating composition of claim 1 wherein the suppressor compound comprisesa structure selected from the group consisting of:

and combinations thereof; wherein R₁ is a substituted or unsubstitutedalkyl group; R₂ is selected from the group consisting of hydrogen andalkyl group; R₃ is a polyether comprising repeat units selected from thegroup consisting of ethylene oxide repeat units, propylene oxide repeatunits, and a combination thereof; and R₄ is selected from the groupconsisting of hydrogen, substituted or unsubstituted alkyl group, arylgroup, aralkyl, or heteroaryl group.
 16. The electrolytic platingcomposition of claim 15 wherein the R₁ alkyl group has between 1 and 8carbons, and R₁ is substituted with another amino group to which apolyether group is covalently bonded, the polyether comprising ethyleneoxide repeat units, propylene oxide repeat units, or a combinationthereof arranged in random, alternating, or block configurations. 17.The electrolytic plating composition of claim 2 wherein the polyethersuppressor is present in a concentration between about 50 mg/L and about200 mg/L.
 18. The electrolytic plating composition of claim 1 whereinthe polyether suppressor comprises the structure:

wherein n is between 1 and about 30 and m is between 1 and about
 30. 19.The electrolytic plating composition of claim 1 wherein the polyethersuppressor comprises the structure:

wherein n is between 1 and about 30 and m is between 1 and about 30.